Interspinous spacer

ABSTRACT

An implantable spacer for placement between adjacent spinous processes in a spinal motion segment is provided. The spacer includes a body defining a longitudinal axis and passageway. A first arm and a second arm are connected to the body. Each arm has a pair of extensions and a saddle defining a U-shaped configuration for seating a spinous process therein. Each arm has a proximal caming surface and is capable of rotation with respect to the body. An actuator assembly is disposed inside the passageway and connected to the body. When advanced, a threaded shaft of the actuator assembly contacts the caming surfaces of arms to rotate them from an undeployed configuration to a deployed configuration. In the deployed configuration, the distracted adjacent spinous processes are seated in the U-shaped portion of the arms.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/887,201 entitled “Interspinous Spacer” filed on Oct. 19, 2015, nowU.S. Pat. No. 9,956,011, which is a continuation of U.S. patentapplication Ser. No. 13/619,195 entitled “Interspinous Spacer” filed onSep. 14, 2012, now U.S. Pat. No. 9,161,783, which is a continuation ofU.S. patent application Ser. No. 12/220,427 entitled “InterspinousSpacer” filed on Jul. 24, 2008, now U.S. Pat. No. 8,277,488, which is acontinuation-in-part of U.S. patent application Ser. No. 12/217,662entitled “Interspinous Spacer” filed on Jul. 8, 2008, now U.S. Pat. No.8,273,108, which is a continuation-in-part of U.S. patent applicationSer. No. 12/148,104 entitled “Interspinous Spacer” filed on Apr. 16,2008, now U.S. Pat. No. 8,292,922. U.S. patent application Ser. No.12/220,427 is also a continuation-in-part of U.S. patent applicationSer. No. 11/593,995 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Nov. 7, 2006, now U.S. Pat. No.8,425,559, which is a continuation-in-part of U.S. patent applicationSer. No. 11/582,874 entitled “Minimally invasive tooling for delivery ofinterspinous Spacer” filed on Oct. 18, 2006, now U.S. Pat. No.8,128,662.

Other patent applications include U.S. patent application Ser. No.11/314,712 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Dec. 20, 2005, now U.S. Pat. No.8,152,837, which is a continuation-in-part of U.S. patent applicationSer. No. 11/190,496 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Jul. 26, 2005, now U.S. Pat. No.8,409,282, which is a continuation-in-part of U.S. patent applicationSer. No. 11/079,006 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Mar. 10, 2005, now U.S. Pat. No.8,012,207, which is a continuation-in-part of U.S. patent applicationSer. No. 11/052,002 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Feb. 4, 2005, now U.S. Pat. No.8,317,864, which is a continuation-in-part of U.S. patent applicationSer. No. 11/006,502 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Dec. 6, 2004, now U.S. Pat. No.8,123,807, which is a continuation-in-part of U.S. patent applicationSer. No. 10/970,843 entitled “Systems and methods for posterior dynamicstabilization of the spine” filed on Oct. 20, 2004, now U.S. Pat. No.8,167,944, all of which are hereby incorporated by reference in theirentireties. U.S. patent application Ser. No. 12/220,427 also claimspriority to and the benefit of U.S. Provisional Patent Application No.60/961,741 entitled “Interspinous Spacer” filed on Jul. 24, 2007. U.S.patent application Ser. No. 12/217,662 also claims priority to and thebenefit of U.S. Provisional Application No. 60/958,876 entitled“Interspinous Spacer” filed on Jul. 9, 2007. U.S. patent applicationSer. No. 12/148,104 also claims priority to and the benefit of U.S.Provisional Patent Application No. 60/923,971 entitled “InterspinousSpacer” filed on Apr. 17, 2007, and U.S. Provisional Patent ApplicationNo. 60/923,841 entitled “Spacer insertion instrument” filed on Apr. 16,2007.

All of the above applications and patents are hereby incorporated byreference in their entireties.

FIELD

The present invention generally relates to medical devices, inparticular, implants for placement between adjacent spinous processes ofa patient's spine.

BACKGROUND

With spinal stenosis, the spinal canal narrows and pinches the spinalcord and nerves, causing pain in the back and legs. Typically, with age,a person's ligaments may thicken, intervertebral discs may deteriorateand facet joints may break down—all contributing to the condition of thespine characterized by a narrowing of the spinal canal. Injury,heredity, arthritis, changes in blood flow and other causes may alsocontribute to spinal stenosis.

Doctors have been at the forefront with various treatments of the spineincluding medications, surgical techniques and implantable devices thatalleviate and substantially reduce debilitating pain associated with theback. In one surgical technique, a spacer is implanted between adjacentinterspinous processes of a patient's spine. The implanted spacer opensthe spinal canal, maintains the desired distance between vertebral bodysegments, and as a result, avoids impingement of nerves and relievespain. For suitable candidates, an implantable interspinous spacer mayprovide significant benefits in terms of pain relief.

Any surgery is an ordeal. However, the type of device and how it isimplanted has an impact. For example, one consideration when performingsurgery to implant an interspinous spacer is the size of the incisionthat is required to allow introduction of the device. Small incisionsand minimally invasive techniques are generally preferred as they affectless tissue and result in speedier recovery times. As such, there is aneed for interspinous spacers that work well with surgical techniquesthat are minimally invasive for the patient. The present invention setsforth such a spacer.

SUMMARY

According to one aspect of the invention, an implantable spacer forplacement between adjacent spinous processes is provided. The spacerincludes a body defining a longitudinal axis. A first arm and a secondarm are connected to the body and capable of movement with respect tothe body. Each arm defines a configuration for receiving a spinousprocess and has a proximal caming surface. The spacer further includesan actuator assembly connected to the body. The actuator assemblyincludes an actuator having at least one bearing surface, a shaftconnected to the actuator and configured for movement with respect tothe body; and a spindle. The actuator assembly is configured to moverelative to the body such that rotation of the spindle moves theactuator such that the at least one bearing surface contacts at leastone of the caming surfaces to move both of the arms from an undeployedconfiguration to a deployed configuration in which the arms receiveadjacent spinous processes.

According to another aspect of the invention, an implantable spacer forplacement between adjacent spinous processes is disclosed. The implantincludes a body defining a longitudinal axis. A first arm and a secondarm are both connected to the body and capable of movement with respectto the body. Each arm has a configuration for receiving a spinousprocess and each arm has a proximal caming surface. The spacer furtherincludes an actuator connected to the body and configured to moverelative to the body to deploy the arms from an undeployedconfiguration. In the deployed configuration, the arms seat adjacentspinous processes. The spacer also includes a lock configured to provideresistance to keep the arms in place.

According to another aspect of the invention, a spinal implant forrelieving pain and implantable between a superior spinous process and aninferior spinous process is disclosed. The implant includes a bodyconnected prior to implantation to at least one arm. The at least onearm is movable with respect to the body into at least one configurationthat is adapted to laterally stabilize and secure the implant withrespect to an adjacent spinous process. In one variation, the implantincludes a first arm for laterally stabilizing the body with respect tothe superior spinous process and a second arm for laterally stabilizingthe body with respect to the inferior spinous process.

According to another aspect of the invention, a spinal implant forrelieving pain and implantable between a superior spinous process and aninferior spinous process is disclosed. The implant includes a bodyconnected prior to implantation to at least one arm. The at least onearm is movable with respect to the body into at least one configurationthat is adapted to laterally stabilize and secure the body with respectto an adjacent spinous process. In one variation, the implant includes afirst arm for laterally stabilizing the body with respect to thesuperior spinous process and a second arm for laterally stabilizing thebody with respect to the inferior spinous process. The implant includesa collapsed configuration in which a first end of the first arm and afirst end of the second arm form the leading edge of the implant.

According to another aspect of the invention, a spinal implant forrelieving pain and implantable between a superior spinous process and aninferior spinous process is disclosed. The implant includes a bodyconnected prior to implantation to at least one arm. The at least onearm is movable with respect to the body into at least one configurationthat is adapted to laterally stabilize and secure the body with respectto an adjacent spinous process. In one variation, the implant includes afirst arm for laterally stabilizing the body with respect to thesuperior spinous process and a second arm for laterally stabilizing thebody with respect to the inferior spinous process. A second end of thefirst arm is hinged to the distal end of the body and a second end ofthe second arm is hinged to the distal end of the body. In onevariation, the first and second arms are configured to rotateapproximately 90 degrees about their hinged ends into a deployedconfiguration. In one variation, wherein when rotated approximately 90degrees, the first and second arms are in a configuration that isadapted to laterally stabilize/secure the body with respect to adjacentspinous processes. In another variation, wherein after rotation ofapproximately 90 degrees, each of the first and second arms areconfigured to translate away from the body such that the arms are closerto their respective spinous processes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in conjunction with the accompanying drawings. It isemphasized that, according to common practice, the various features ofthe drawings are not to-scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.

FIG. 1a illustrates a perspective view of a spacer according to thepresent invention.

FIG. 1b illustrates a side view of a spacer according to the presentinvention.

FIG. 1c illustrates a top view of a spacer according to the presentinvention.

FIG. 1d illustrates a cross-sectional view of the spacer of FIG. 1ctaken along line A-A according to the present invention.

FIG. 1e illustrates an end view of a spacer according to the presentinvention.

FIG. 1f illustrates an exploded perspective view of a spacer accordingto the present invention.

FIG. 2a illustrates a perspective view of half of a body of a spaceraccording to the present invention.

FIG. 2b illustrates a side view of half of a body of a spacer accordingto the present invention.

FIG. 3a illustrates a perspective view of a superior arm of a spaceraccording to the present invention.

FIG. 3b illustrates a back view of a superior arm of a spacer accordingto the present invention.

FIG. 3c illustrates a side view of a superior arm of a spacer accordingto the present invention.

FIG. 3d illustrates a perspective view of an inferior arm of a spaceraccording to the present invention.

FIG. 3e illustrates a back view of an inferior arm of a spacer accordingto the present invention.

FIG. 3f illustrates a side view of an inferior arm of a spacer accordingto the present invention.

FIG. 4a illustrates a perspective view of a spindle of an actuatorassembly of a spacer according to the present invention.

FIG. 4b illustrates a top view of a spindle of an actuator assembly of aspacer according to the present invention.

FIG. 4c illustrates a cross-sectional view of the spindle of FIG. 4btaken along line F-F according to the present invention.

FIG. 4d illustrates a perspective view of a lock according to thepresent invention.

FIG. 4e illustrates a top view of a lock according to the presentinvention.

FIG. 4f illustrates a partial cross-sectional top view of a lock, bodyand spindle according to the present invention.

FIG. 5a illustrates a side view of a spacer in a closed, undeployedconfiguration according to the present invention.

FIG. 5b illustrates a side view of a spacer in a partially deployedconfiguration according to the present invention.

FIG. 5c illustrates a side view of a spacer in a deployed configurationaccording to the present invention.

FIG. 6a illustrates a side, cross-sectional view of a spacer in aclosed, undeployed configuration according to the present invention.

FIG. 6b illustrates a side, cross-sectional view of a spacer in apartially deployed configuration according to the present invention.

FIG. 6c illustrates a side, cross-sectional view of a spacer in adeployed configuration according to the present invention.

FIG. 7a illustrates a side, semi-transparent view of a spacer in aclosed undeployed configuration according to the present invention.

FIG. 7b illustrates a side, semi-transparent view of a spacer in apartially deployed configuration according to the present invention.

FIG. 7c illustrates a side, semi-transparent view of a spacer in adeployed configuration according to the present invention.

FIG. 8 illustrates a side view of half of a body of a spacer accordingto the present invention.

FIG. 9a illustrates a perspective view of a superior arm of a spaceraccording to the present invention.

FIG. 9b illustrates a perspective view of an inferior arm of a spaceraccording to the present invention.

FIG. 10a illustrates a perspective view of half of a body of a spaceraccording to the present invention.

FIG. 10b illustrates a side view of half of a body of a spacer accordingto the present invention.

FIG. 11a illustrates a perspective view of a superior arm of a spaceraccording to the present invention.

FIG. 11b illustrates a back view of a superior arm of a spacer accordingto the present invention.

FIG. 11c illustrates a side view of a superior arm of a spacer accordingto the present invention.

FIG. 11d illustrates a perspective view of an inferior arm of a spaceraccording to the present invention.

FIG. 11e illustrates a back view of an inferior arm of a spaceraccording to the present invention.

FIG. 11f illustrates a side view of an inferior arm of a spaceraccording to the present invention.

FIG. 12a illustrates a side, semi-transparent view of a spacer in aclosed, undeployed configuration according to the present invention.

FIG. 12b illustrates a side, semi-transparent view of a spacer in apartially deployed configuration according to the present invention.

FIG. 12c illustrates a side, semi-transparent view of a spacer in adeployed configuration according to the present invention.

FIG. 12d illustrates a side, semi-transparent view of a spacer in adeployed and extended configuration according to the present invention.

FIG. 13a illustrates a perspective view of half of a body of a spaceraccording to the present invention.

FIG. 13b illustrates a side view of half of a body of a spacer accordingto the present invention.

FIG. 14a illustrates a perspective view of a superior arm of a spaceraccording to the present invention.

FIG. 14b illustrates a back view of a superior arm of a spacer accordingto the present invention.

FIG. 14c illustrates a side view of a superior arm of a spacer accordingto the present invention.

FIG. 14d illustrates a perspective view of an inferior arm of a spaceraccording to the present invention.

FIG. 14e illustrates a back view of an inferior arm of a spaceraccording to the present invention.

FIG. 14f illustrates a side view of an inferior arm of a spaceraccording to the present invention.

FIG. 15a illustrates a side view of a spacer in a closed, undeployedconfiguration according to the present invention.

FIG. 15b illustrates a side view of a spacer in a partially deployedconfiguration according to the present invention.

FIG. 15c illustrates a side view of a spacer in a deployed configurationaccording to the present invention.

FIG. 15d illustrates a side view of a spacer in a deployed and extendedconfiguration according to the present invention.

FIG. 16a illustrates a side, cross-sectional view of a spacer in aclosed, undeployed configuration according to the present invention.

FIG. 16b illustrates a side, cross-sectional view of a spacer in apartially deployed configuration according to the present invention.

FIG. 16c illustrates a side, cross-sectional view of a spacer in adeployed configuration according to the present invention.

FIG. 16d illustrates a side, cross-sectional view of a spacer in adeployed and extended configuration according to the present invention.

FIG. 17a illustrates a side, semi-transparent view of a spacer in aclosed undeployed configuration according to the present invention.

FIG. 17b illustrates a side, semi-transparent view of a spacer in apartially deployed configuration according to the present invention.

FIG. 17c illustrates a side, semi-transparent view of a spacer in adeployed configuration according to the present invention.

FIG. 17d illustrates a side, semi-transparent view of a spacer in adeployed and extended configuration according to the present invention.

FIG. 18a illustrates a side view of an insertion instrument connected toa spacer in a closed, undeployed configuration according to the presentinvention.

FIG. 18b illustrates a side view of an insertion instrument connected toa spacer in a partially deployed configuration according to the presentinvention.

FIG. 18c illustrates a side view of an insertion instrument connected toa spacer in a deployed configuration according to the present invention.

FIG. 18d illustrates a side view of an insertion instrument connected toa spacer in a deployed and extended configuration according to thepresent invention.

FIG. 19 illustrates a spacer according to the present invention deployedin an interspinous process space between two vertebral bodies and asupraspinous ligament.

DETAILED DESCRIPTION

Before the subject devices, systems and methods are described, it is tobe understood that this invention is not limited to particularembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present invention will be limited onlyby the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to “aspinal segment” may include a plurality of such spinal segments andreference to “the screw” includes reference to one or more screws andequivalents thereof known to those skilled in the art, and so forth.

All publications mentioned herein are incorporated herein by referenceto disclose and describe the methods and/or materials in connection withwhich the publications are cited. The publications discussed herein areprovided solely for their disclosure prior to the filing date of thepresent application. Nothing herein is to be construed as an admissionthat the present invention is not entitled to antedate such publicationby virtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates which may need to beindependently confirmed.

The present invention is described in the accompanying figures and textas understood by a person having ordinary skill in the field of spinalimplants and implant delivery instrumentation.

With reference to FIGS. 1a-1f , various views of a spacer 10 accordingto the present invention are shown. The spacer 10 includes a body 12connected to a superior extension member or arm 14, an inferiorextension member or arm 16, and an actuator assembly 18.

Turning now to FIGS. 2a-2b , the body 12 will now be described. The body12 is shown to have a clamshell construction with a left body piece 20(shown in FIG. 2a ) joined to a right body piece 22 (shown in FIG. 2b )to capture arms 14, 16 inside. With the right and left body pieces 20,22 joined together, the body 12 is generally cylindrical. The spacerbody 12 has a cross-sectional size and shape that allows forimplantation between adjacent spinous processes and facilitates deliveryinto a patient through a narrow port or cannula.

The inside of the body 12 defines an arm receiving portion 24 and anactuator assembly receiving portion 26 with features formed in each ofthe left and right body pieces 20, 22 that together define the arm andactuator assembly receiving portions 24, 26. In one variation, the armreceiving portion 24 includes slots or openings 28 that receive pinsformed on the arms 14, 16 such that the pins rotate and/or translateinside the openings 28. The actuator assembly receiving portion 26includes a passageway 30. The actuator assembly receiving portion 26includes a spindle receiving portion 80 formed by the two joined pieces20, 22 to form a ledge. The actuator assembly receiving portion 26 alsoincludes at least one lock receiving portion 82. Other features includea tongue and groove for mating with the opposite clamshell.

The outside of the body 12 defines a ledge 32 along at least a portionof the periphery and at least one or continuos undercut 98. Notches 34are formed at opposite locations as also shown in FIG. 1b . The notches34 are configured for pronged attachment to a spacer deliveryinstrument. When joined together, the left and right body pieces 20, 22define a proximal opening 36 (as seen in FIG. 1e ) and a distal opening38 (as seen in FIG. 1a ) in the body 12. A longitudinal scallop 84 (alsoshown in FIGS. 1a, 1e, 1f and 2a ) extending from the proximal end ofthe spacer to the distal end is formed in the outer surface of the body12 to facilitate placement of the spacer 10 between and to conform tothe anatomy of adjacent interspinous processes. On one variation, twooppositely located longitudinal scallops 84 are formed in the outersurface of the body 12 such that one scallop 84 faces the superiorspinous process and the other scallop 84 faces the inferior spinousprocess. In one variation, the distance between oppositely locatedlongitudinal scallops 84 (as best seen in FIG. 1e ) is approximately 8.0millimeters imparting the spacer 10 with a low profile advantageous forinsertion between closely spaced or “kissing” spinous processes.

Turning now to FIGS. 3a-3c , the superior arm 14 is shown and in FIGS.3d-3f , the inferior arm 16 is shown. The superior and inferior arms 14,16 include pins 40 for mating with the body 12, in particular, formating with the slots/openings 28 of the arm receiving portion 24. Eachof the superior and inferior arms 14, 16 includes at least one camingsurface 41, 43, respectively, for contact with the actuator assembly 18.The superior and inferior arms 14, 16 include elongated superiorextensions 42 a, 42 b and elongated inferior extensions 44 a, 44 b,respectively. Extensions 42 a and 44 a are located on the left adjacentto the left body piece 20 and extensions 42 b and 44 b are located onright adjacent to the right body piece 22. Superior extensions 42 a, 42b extend substantially parallel to each other in both an undeployedconfiguration and in a deployed configuration as do inferior extensions44 a, 44 b. Extending between extensions 42 a, 42 b is a strut, bridge,bracket or saddle 46 that forms a superior substantially U-shapedconfiguration that is sized and configured to receive a superior spinousprocess. As seen in FIG. 3c , the anterior face of the superiorextensions 14 includes a slight concavity or curvature 45 for conformingto the bony anatomy of the superior spinous process and or lamina.Extending between inferior extensions 44 a, 44 b is a strut, bridge,bracket or saddle 48 that forms an inferior substantially U-shapedconfiguration together with the extensions 44 a, 44 b that is sized andconfigured to receive an inferior spinous process of a spinal motionsegment. As seen in FIG. 3f , the anterior face of the inferiorextensions 16 includes a slight convexity or curvature 47 for conformingto the bony anatomy of the inferior spinous process and/or lamina. Inone variation, the length of the saddle 46 of the superior arm 14 isapproximately 8.5 millimeters and the length of the saddle 48 of theinferior arm 16 is approximately 6.6 millimeters. Also, the tip-to-tipdistance of the superior extensions 42 a, 42 b is approximately 9.8millimeters and the tip-to-tip distance of the inferior extensions 44 a,44 b is approximately 9.4 millimeters. In sum, the seat comprising thesaddle 46 and superior extensions 42 a, 42 b formed by the superior arm14 is larger than the seat comprising the saddle 48 and inferiorextensions 44 a, 44 b formed by the inferior arm 16. The larger superiorseat of the spacer conforms closely to a wider lower end of the spinousprocess and the smaller inferior seat of the spacer conforms closely toa narrower upper end of the adjacent inferior spinous process when thespacer 10 is inserted between adjacent spinous processes as spinousprocesses are naturally narrower on top and wider on the bottom.

The superior and inferior arms 14, 16 are movably or rotatably connectedto the body 12, for example by hinge means or the like to providerotational movement from an undeployed configuration to a deployedconfiguration that arcs through about a 90 degree range or more withrespect to the body 12. The arms 14, 16 are rotationally movable betweenat least an undeployed, collapsed or folded state (as shown in FIGS.1a-1e, 5a, 6a and 7a ) and at least one deployed state (as shown inFIGS. 5c, 6c, 7c ). In the undeployed state, the arm pairs 14, 16 arealigned generally or substantially axially (i.e., axially with thelongitudinal axis, defined by the body 12 or to the translation pathinto the interspinous space of the patient) to provide a minimal lateralor radial profile. The longitudinal axis X of the spacer 10 and body 12is shown in FIG. 1c . In the deployed state, the arm pairs 14, 16 arepositioned such that each of the U-shaped saddles are in a plane (orplanes) or have a U-shaped projection in a plane that is (are) generallyor substantially transverse to the longitudinal axis X defined by thebody 12 or to the collapsed position or to the implantation path intothe interspinous space of the patient. In one variation, the spacer 10is configured such that the arms 14, 16 are linearly moveable ortranslatable within the same transverse plane from a first deployedstate (such as the state shown in FIG. 12c ) to and from a seconddeployed state (such as the state shown in FIG. 12d ) characterized byan additional translation of at least one of the arms 14, 16 withrespect to the body 12 along a direction of the arrows as shown in FIG.12d away from or towards the body 12. The arms 14, 16 can be extended inthe general vertical direction along an axis along the general length ofthe spine wherein the arms 14, 16 are extended away from each other andaway from the body 12 as denoted by the arrows in FIG. 12d . The arms14, 16 can be un-extended in a direction towards each other and towardsthe body 12 for un-deployment or repositioning of the spacer 10. Thisfeature advantageously allows for the most minimally invasiveconfiguration for the spacer without compromising the ability of thespacer 10 to seat and contain the spinous processes in between levelswhere the anatomy of the spinous processes is such that the interspinousprocess space increases in the anterior direction or withoutcompromising the ability of the spacer to provide adequate distraction.The arms 14, 16 are connected to the body 12 and/or to each other in amanner that enables them to be moved simultaneously or independently ofeach other, as well as in a manner that provides passive deploymentand/or vertical extension or, alternatively, active or actuateddeployment and/or vertical extension.

Turning back to FIG. 1f , the actuator assembly 18 will now bedescribed. The actuator assembly 18 includes an actuator 48 connected toa shaft 50 and retainer 52, a spindle 86 and a optional lock 88. Theactuator 48 includes a distal end 54 and a proximal end 56 and at leasttwo bearing surfaces 58. The bearing surfaces 58 angle towards eachother from the proximal end 56 to the distal end 54. In one variation asshown in FIG. 1f , the actuator 48 is integrally formed with the shaft50. The shaft 50 is substantially cylindrical in shape and includes athreaded outer surface for engagement with a threaded inner surface ofthe spindle 86. The distal end 54 of the actuator 48 is furtherconfigured to engage the superior and inferior arms 14, 16 such thatforward translation of the actuator 48 relative to the body 12 effectsdeployment of the arms into at least one deployed configuration.

Still referencing FIG. 1f and with particular reference to FIGS. 4a-4c ,the spindle 86 has circular top profile and includes a central bore 90having a threaded inner surface which is sized for threaded connectionto the shaft 50. The spindle 86 includes an outer ledge 92 andoppositely disposed notches 94 for connecting to a deploymentinstrument. The outer sidewall of the spindle 86 includes a plurality ofspindle teeth 102. The spindle 86 is configured to be disposed in thespindle receiving portion 80 of the body 12.

Still referencing FIG. 1f , the retainer 52, which is preferably made ofmetal such as surgical steel or titanium, includes a proximal end 70 andat least one prong 72 extending distally from the proximal end 70. Eachprong 72 includes a hook portion 96 for hooking to the undercut 98 ofthe body 12 to attach the retainer 52 to the body 12. Each prong 72 isallowed to deflect and spring back to snap engage the undercut 98 andthereby connect to the body 12 and retain the actuator assembly 18 tothe body 12. An aperture 100 is sized for clear passage of the actuator48 and shaft 50. The actuator assembly 18 is at least partially disposedinside the body 12 and is configured to move with respect to the body12.

Still referencing FIG. 1f and with particular reference to FIGS. 4d, 4eand 4f , the lock 88 is a small elongate piece of metal or othersuitable material such as steel or titanium capable of deflection. Thelock 88 is sized to be disposed in the lock receiving portion 82 asshown in FIG. 4f . The lock 88 includes a tooth 104 which is configuredto engage the spindle teeth 102. Rotation of the spindle 86 deflects thelock 88 outwardly which then snaps back into between the spindle teeth102 to lock the spindle 86 in place.

Assembly of the spacer 10 with reference to FIGS. 1a-1f will now bedescribed. The arms 14, 16 are disposed in the arm receiving portion 24of one body piece. The other of the left or right body piece 20, 22 issecurely connected/welded to the one body piece thereby capturing thearms 14, 16 inside the arm receiving portion 24 such that the arms 14,16 are capable of at least rotational movement with respect to the body12 and in one variation, capable of rotational movement and translationwith respect to the body 12. In a variation in which the body 12 is madeof one piece, the arms 14, 16 are movably connected to the body 12 witha pin, for example. The shaft 50 and the actuator 48 are togetherinserted into the proximal opening 36 and passageway 30 of the body 12.The spindle 86 is disposed in the spindle receiving portion 80 of thebody 12 and threaded onto the shaft 50. The lock 88 is disposed insidethe lock receiving portion 82 of the body 12. The retainer 52 isconnected to the body 12 such that the hooked portion(s) 96 snap intothe undercut(s) 98 and such that the shaft 50 can pass through theretainer aperture 100. The retainer 52 captures the spindle 86, actuator48, shaft 50 and lock 88 inside the body 12 such that the spindle 86 isallowed to rotate and, thereby, move the actuator and shaft 48, 50inside the body passageway 30.

Referring now to FIGS. 5a-5d , the spacer 10 is shown in a closed,undeployed configuration (FIG. 5a ), a partially deployed configurationor otherwise intermediary configuration (FIG. 5b ), and a deployedconfiguration (FIG. 5c ). In moving from an undeployed to a deployedconfiguration, the actuator assembly 18 and, in particular, the shaft 50of the actuator assembly moves distally with respect to the body to aposition flush or almost flush with the proximal end of the body 12 orto a position completely inside the body 12 disappearing from sightproviding a low profile for the spacer 10 along the longitudinal axis ofthe body 12.

Turning now to the cross-sectional views of the spacer 10 in FIGS. 6a-6c, as the shaft 50 advances within the passageway 30, the bearingsurfaces 58 of the actuator 48 contact the superior and inferior camingsurfaces 41, 43 of the superior and inferior arms 14, 16 turning thearms 14, 16 into rotation with respect to the body 12. Upon rotation,the bearing surfaces 58 of the actuator 48 slide with respect to thesuperior and inferior caming surfaces 41, 43 of the superior andinferior arms 14, 16. The arms 14, 16 rotate through an are ofapproximately 90 degrees with respect to the body 12 into the deployedconfiguration (FIG. 6c ) in which the superior and inferior extensionsof the arms 14, 16 are substantially perpendicular to the longitudinalaxis of the spacer 10 as shown in FIG. 6c . The arms 14, 16 have asubstantially U-shaped projection in a plane perpendicular to thelongitudinal axis of the spacer 10.

Turning now to the semi-transparent views of the spacer 10 in FIGS.7a-7c , the rotation of the pins 40 of the arms 14, 16 in the openings28 of the body 12 is shown in moving from the configuration of FIG. 7ato the configuration of FIG. 7c . Reverse rotation of the spindle 86moves the shaft 50 proximally with respect to the body 12 allowing thearms to close to any intermediary configuration between a deployed,configuration and an undeployed, closed configuration. This featureadvantageously permits the surgeon to ease installation and positioningof the spacer with respect to patient anatomy.

Turning now to FIG. 8, another variation of the body 12 will now bediscussed wherein like reference numbers are used to describe likeparts. The body 12 of the variation shown in FIG. 8 has the sameclamshell construction with the left body piece 20 joined to a rightbody piece 22 to capture arms 14, 16 inside. With the right and leftbody pieces 20, 22 joined together, the body 12 is generallycylindrical. It has a cross-sectional size and shape that allows forimplantation between adjacent spinous processes and facilitates deliveryinto a patient through a narrow port or cannula. The left and right bodypieces 20, 22 are identical and therefore, FIG. 8 illustrates either theleft or right body piece 20, 22.

Still referencing FIG. 8, the inside of the body 12 defines an armreceiving portion 24 and an actuator assembly receiving portion 26 withfeatures formed in each of the left and right body pieces 20, 22 thattogether define the arm and actuator assembly receiving portions 24, 26.The arm receiving portion 24 includes slots or openings or apertures 28that receive pins formed on the arms 14, 16 such that the pins rotateand/or translate inside the slots or apertures 28. In the variationshown in FIG. 8, in addition to two circular openings 28 a, there isprovided a curved slot 28 b in each of the left and right body pieces20, 22. The circular openings 28 a and curved slot 28 b are configuredto receive pins 40 of arms 14, 16 that are illustrated in FIGS. 9a and 9b.

Turning now to FIGS. 9a and 9b , the superior arm 14 is shown in FIG. 9a, and the inferior arm 16 is shown in FIG. 9b . The superior andinferior arms 14, 16, include pins 40 a and 40 b for mating with thebody 12, in particular, for mating with the openings 28 a and slots 28b, respectively. Each side of the superior and inferior arms 14, 16includes a circular first pin 40 a configured for insertion into opening28 a such that the arms 14, 16 rotate with respect to the body 12. Atleast one side of each of the arms 14, 16 includes a second pin 40 bconfigured for insertion into opening slot 28 b. Slot 28 b and pin 40 bserve as a stop mechanism such that the rotation of the arms 14, 16 withrespect to the body 12 is limited by pin 40 b in slot 28 b. While beingdeployed, the arms 14, 16 rotate to a position transverse to thelongitudinal axis from a position parallel to the longitudinal axiswherein such rotation is arrested by pin 40 b abutting the end of slot28 b. Other features of the arms 14, 16 shown in FIGS. 9a and 9b aresubstantially the same as described above and like reference numbers areused to describe the like parts.

Turning now to FIGS. 10a and 10b , another variation of the spacer body12 will now be discussed wherein like reference numbers are used todescribe like parts. The body 12 of the spacer variation shown in FIGS.10a and 10b has a clamshell construction as described above with theleft body piece 20 joined to a right body piece 22 to capture arms 14,16 inside. With the right and left body pieces 20, 22 joined together,the body 12 is generally cylindrical. It has a cross-sectional size andshape that allows for implantation between adjacent spinous processesand facilitates delivery into a patient through a narrow port orcannula. FIG. 10a shows the left body piece 20 and FIG. 10b shows theright body piece 22, however, the left and right body pieces 20, 22 areidentical.

Still referencing FIGS. 10a and 10c , the inside of the body 12, formedby the conjunction of the left and right body pieces 20, 22, defines anarm receiving portion 24 and an actuator assembly receiving portion 26with features formed in each of the left and right body pieces 20, 22that together define the arm and actuator assembly receiving portions24, 26. The arm receiving portion 24 includes slots or openings orapertures 28 that receive pins formed on the arms 14, 16 such that thepins rotate and/or translate inside the slots or apertures 28. Inparticular, in the variation shown in FIGS. 10a and 10b , two elongatedopenings 28 c and a curved slot opening 28 d are provided in each of theleft and right body pieces 20, 22. The elongated openings 28 c andcurved opening 28 d are configured to receive pins 40 of arms 14, 16 andserve as channels in which pins 40 can move. The curved slot 28 dincludes a straight distal portion for translating and extending thearms 14, 16 with respect to the body. Arms 14 and 16 with pins 40configured to correspond to the left and right body pieces 20, 22 areshown in FIGS. 11a -11 f.

Turning now to FIGS. 11a-11f , the superior arm 14 is shown in FIGS.11a-11c , and the inferior arm 16 is shown in FIGS. 11d-11f . Thesuperior and inferior arms 14, 16, include pins 40 c and 40 d for matingwith the body 12, in particular, for mating with the elongated openings28 c and curved slots 28 d, respectively. Each side of the superior andinferior arms 14, 16 includes at least a first pin 40 c configured forinsertion into opening 28 c such that the arms 14, 16 rotate withrespect to the body 12 as well as translate with respect to the body 12.At least one side of each of the arms 14, 16 includes a second pin 40 dconfigured for insertion into curved slot 28 d such that the arms 14, 16rotate with respect to the body 12 as well as translate with respect tothe body 12. Slots 28 d and openings 28 c guide the movement of pins 40d and 40 c, respectively therein as will be described with respect toFIGS. 12a-12d . Other features of the arms 14, 16 shown in FIGS. 11a-11fare substantially the same as described above and like reference numbersare used to describe the like parts.

Referring now to FIGS. 12a-12d , the spacer 10 is shown in a closed,undeployed configuration (FIG. 12a ), a partially deployed or otherwiseintermediary configuration (FIG. 12b ), a deployed configuration (FIG.12c ), and a deployed and extended configuration (FIG. 12d ). In movingfrom an undeployed to a deployed configuration, the semi-transparentviews of the spacer 10 in FIGS. 12a-12d show the rotation andtranslation of the pins 40 of the arms 14, 16 in the slots 28 of thebody 12. The translation of the pins 40 of the arms 14, 16 in the slots28 of the body 12 is shown in moving from the first deployedconfiguration of FIG. 12c to the second deployed, extended configurationof FIG. 12d wherein the extension of the arms 14, 16 is in the directionof the arrows in FIG. 12d . Such outward translation with respect to thebody 12 is guided by the length and shape of the slots 28. Opening 28 cis elongated and slot 28 d includes a straight distal end configured toaccommodate and guide the extension of arms 14, 16 away from the body12. Reverse rotation of the spindle 86 moves the shaft 50 proximallywith respect to the body 12 allowing the arms 14, 16 to close to anyintermediary configuration between a deployed, extended configurationand an undeployed, closed configuration. This feature advantageouslypermits the surgeon to ease installation and positioning of the spacerwith respect to patient anatomy as the arms 14, 16 can be deployed,undeployed and then re-deployed as often as necessary to position thespacer 10.

Turning now to FIGS. 13a and 13b , another variation of the spacer withyet another body 12 configuration will now be discussed wherein likereference numbers are used to describe like parts. The body 12 of thevariation shown in FIGS. 13a and 13b has a clamshell construction asdescribed above with a left body piece 20 joined to a right body piece22 to capture arms 14, 16 inside. With the right and left body pieces20, 22 joined together, the body 12 is generally cylindrical. It has across-sectional size and shape that allows for implantation betweenadjacent spinous processes and facilitates delivery into a patientthrough a narrow port or cannula. FIG. 13a shows the left body piece 20and FIG. 13b shows the right body piece 22, however, the left and rightbody pieces 20, 22 are identical.

Still referencing FIGS. 13a and 13b , the inside of the body 12, formedby the conjunction of the left and right body pieces 20, 22, defines anarm receiving portion 24 and an actuator assembly receiving portion 26that includes a spindle receiving portion 80 and lock receiving portion82 with features formed in each of the left and right body pieces 20, 22that together define the arm and actuator assembly receiving portions24, 26. The arm receiving portion 24 includes slots or openings orapertures 28 that receive pins formed on the arms 14, 16 such that thepins rotate and/or translate inside the slots or apertures 28. Inparticular, in the variation shown in FIGS. 13a and 13b , a firstopening 28 e and a second opening 28 f are provided in each of the leftand right body pieces 20, 22. The first opening 28 e includes a fannedrecess. Both openings 28 e and curved slot 28 f are configured toreceive pins 40 of arms 14, 16 and serve as channels that constrain themovement of the pins 40. In the variation shown, the openings 28 e, 28 fare configured to permit extension of the arms 14, 16 away from thebody. Arms 14, 16 with pins 40 that are configured to correspond to theleft and right body pieces 20, 22 are shown in FIGS. 14a -14 f.

Turning now to FIGS. 14a-14f , the superior arm 14 is shown in FIGS.14a-14c , and the inferior arm 16 is shown in FIGS. 14d-14f . Thesuperior and inferior arms 14, 16, include a first pin 40 e and a secondpin 40 f for mating with the body 12, in particular, for mating with thefirst opening 28 e and second opening 28 f, respectively. At least oneside of each of the superior and inferior arms 14, 16 includes a firstpin 40 e configured for insertion into opening 28 e such that the arms14, 16 rotate with respect to the body 12 as well as translate withrespect to the body 12. At least the other side of each of the arms 14,16 includes a second pin 40 f configured for insertion into curved slot28 f such that the arms 14, 16 rotate with respect to the body 12 aswell as translate with respect to the body 12. The first pin 40 eincludes a central portion integrally formed with a peripheral orprojecting portion in what resembles a merging of two pins into onelarger pin. This larger pin 40 e advantageously provides a largerbearing surface capable of bearing larger loads in arresting rotation ofthe arms 14, 16. The first and second openings 28 e, 28 f guide themovement of pins 40 e and 40 f, respectively as will be described withrespect to FIGS. 17a-17d . Other features of the arms 14, 16 shown inFIGS. 14a-14f are substantially the same as described above and likereference numbers are used to describe the like parts.

Referring now to FIGS. 15a-15d , the spacer 10 having a body 12 of FIGS.13a and 13b is shown in a closed, undeployed configuration (FIG. 15a ),a partially deployed or otherwise intermediary configuration (FIG. 15b), a deployed configuration (FIG. 15c ), and a deployed and extendedconfiguration (FIG. 15d ).

Turning now to the cross-sectional views of the spacer 10 in FIGS.16a-16d , as the spindle 86 is rotated and the shaft 50 advances withinthe passageway 30, the bearing surfaces 58 of the actuator 48 contactthe superior and inferior caming surfaces 41, 43 of the superior andinferior arms 14, 16 turning the arms 14, 16 into rotation with respectto the body 12. Upon rotation, the bearing surfaces 58 of the actuator48 slide with respect to the superior and inferior caming surfaces 41,43 of the superior and inferior arms 14, 16. The arms 14, 16 rotatethrough an arc of approximately 90 degrees with respect to the body 12into the deployed configuration (FIG. 16c ) in which the superior andinferior extensions of the arms 14, 16 are substantially perpendicularto the longitudinal axis of the spacer 10 as shown in FIG. 16c and withfurther actuation, into a deployed and extended configuration (FIG. 16d) in which the superior and inferior extensions of the arms 14, 16 aresubstantially perpendicular to the longitudinal axis of the spacer 10and the arms 14, 16 are moved away from the body 12 in a transversedirection to the longitudinal axis as shown by the arrows in FIG. 16 d.

Turning now to FIGS. 17a-17d , semi-transparent views of the spacer 10are shown. In moving from an undeployed to a deployed configuration, therotation and translation of the pins 40 e, 40 f of the arms 14, 16 inthe slots 28 e, 28 f of the body 12 is shown. Following rotation, thetranslation of the pins 40 e, 40 f of the arms 14, 16 in the slots 28 e,28 f, respectively, is shown in moving from the first deployedconfiguration of FIG. 17c to the second deployed, extended configurationof FIG. 17d in the direction of the arrows in FIG. 17d . Such outwardtranslation with respect to the body 12 is guided by the length andshape of the slots 28 e, 28 f. Reverse rotation of the spindle 86 movesthe shaft 50 proximally with respect to the body 12 allowing the arms toclose to any intermediary configuration between a deployed, extendedconfiguration and an undeployed, closed configuration. This featureadvantageously permits the surgeon to ease installation and positioningof the spacer with respect to patient anatomy.

To deliver and deploy the spacer 10 within the patient, the spacer 10 isreleasably attached to an insertion instrument 80 at the proximal end ofthe spacer 10 via notches 34. The insertion instrument 80 includes afirst assembly 102 connected to a second assembly 104 and a handleassembly 106.

The spacer 10 is provided or otherwise placed in its undeployed, closedstate in juxtaposition to the insertion instrument 80 and connectedthereto as shown in FIG. 18a . The longitudinal axis of the insertioninstrument 80 is advantageously aligned with the longitudinal axis ofthe spacer 10 as shown. The delivery instrument 80 includes a firstsubassembly 102 to releasably clamp to the body 12 of the spacer 10 at adistal end of the insertion instrument 80. The first subassembly 102includes an inner clamp shaft (not shown) having flexible prongs 126 atthe distal end configured for attachment to the body 12 of the spacer 10and, in particular, for insertion into the notches 34 of the spacer body12. The first subassembly 102 includes an outer shaft 112 located overthe inner clamp shaft and configured for relative motion with respect toone another via a control 114 located at the handle assembly 106. Thecontrol 114 is threaded to the outer shaft 112 such that rotation of thecontrol 114 moves the outer shaft 112 along the longitudinal axis of theinsertion instrument 80 over the inner clamp shaft to deflect andundeflect the prongs 126 to connect or disconnect the instrument 80 toor from the body 12. The first control 114 is activated at the handle ofthe insertion instrument 100 such that the first subassembly 102 isconnected to the body 12 of the spacer 10. The first control 114 isrotated in one direction to advance the outer shaft 112 over the innerclamp shaft (not shown) deflecting the prongs 118 inwardly into thenotches 34 on the body 12 of the spacer 10 to secure the spacer body 12to the instrument as shown in FIG. 18a . Reverse rotation of the control114 reverses the direction of translation of the outer shaft 112 torelease the prongs 126 from the notches 34 and, thereby, release thespacer 10 from the instrument 80.

Still referencing FIG. 18a , the insertion instrument 80 includes asecond subassembly 104 that is configured to connect to the actuatorassembly 18 of the spacer 10. In particular, the second subassembly 104includes means located at the distal end of the second subassembly 104to activate the actuator assembly 18. In one variation, the secondsubassembly 104 is a pronged driver having an elongated shaft that isconfigured to be insertable into the notches 94 of the spindle 86 whilethe spacer 10 is connected to the instrument 80. As seen in FIG. 4b ,there are two notches 94 oppositely located from each other in thespindle 86. The distal end of the driver includes prongs that correspondto the notches 94 and configured to be inserted into the notches 94. Thesecond subassembly 104 is insertable at the proximal end of theinstrument 80 and extends through the handle assembly 106 and throughthe inner shaft until the notches are engaged by the distal end. Theremovable driver 104 is rotatable with respect to the instrument 80 torotate the spindle 86 and arrange the spacer 10 to and from deployed andundeployed configurations.

To deliver and deploy the spacer 10 within the patient, the spacer 10 isreleasably attached to a delivery instrument 80 at the proximal end ofthe spacer 10 as described. A small midline or lateral-to-midlineincision is made in the patient for minimally-invasive percutaneousdelivery. In one variation, the supraspinous ligament is avoided. Inanother variation, the supraspinous ligament is split longitudinallyalong the direction of the tissue fibers to create an opening for theinstrument. Dilators may be further employed to create the opening. Inthe undeployed state with the arms 14, 16 in a closed orientation andattached to a delivery instrument 80, the spacer 10 is inserted into aport or cannula, if one is employed, which has been operativelypositioned to an interspinous space within a patient's back and thespacer is passed through the cannula to the interspinous space betweentwo adjacent vertebral bodies. The spacer 10 is advanced beyond the endof the cannula or, alternatively, the cannula is pulled proximately touncover the spacer 10 connected to the instrument 80. Once in position,the second assembly 104 is inserted into the instrument 80 if notpreviously inserted to engage the spindle notches 94 and is rotated torotate the spindle 86. The rotating spindle 86 then advances theactuator 48 and shaft 50 to begin deployment the spacer 10. Rotation inone direction, clockwise, for example, threadingly advances the shaft 50through the spindle central bore 90 which then results in the actuator48 contacting the superior and inferior caming surfaces 41, 43 of thesuperior and inferior arms 14, 16 to begin their deployment. FIG. 18billustrates the superior arm 14 and the inferior arm 16 in a partiallydeployed position with the arms 14, 16 rotated away from thelongitudinal axis. Rotation of the driver 104 turns the spindle 86 whichin turn rotates the actuator shaft 50 threadingly advancing it withrespect to the body 12 which distally advances the actuator 48 whosebearing surfaces 58 contact the superior and inferior camming surfaces41, 43 pushing the superior and inferior arms 14, 16 into rotation aboutthe pins 40 that are guided in the openings 28. The lock 88 snaps intothe spindle teeth 102 advantageously locking the deployment of the armsat any degree of rotation of the spindle 86 to prevent the arms 14, 16from folding and providing a tactile and audio feedback of thedeployment progress. The lock 88 permits further rotation or de-rotationas desired.

The position of the arms 14, 16 in FIG. 18b may be considered to be oneof many partially deployed configurations or intermediary configurationsthat are possible and from which the deployment of the arms 14, 16 isreversible with opposite rotation of the second assembly 104. Withfurther advancement, the arms 14, 16 rotate through an arc ofapproximately 90 degrees into the deployed configuration in which thesuperior and inferior extensions are substantially perpendicular to thelongitudinal axis of the spacer 10 as shown in FIG. 18 c.

Turning to FIG. 18c , there is shown an insertion instrument 80connected to a spacer 10 in a first deployed configuration in which thearms 14, 16 are approximately 90 degrees perpendicular to thelongitudinal axis or perpendicular to the initial undeployedconfiguration. Continued rotation of second assembly 104 rotates thespindle 86 and threads the shaft 50 further distally with respect to thebody 12 of the spacer 10 pushing the bearing surfaces 58 further againstthe superior and inferior camming surfaces 41, 43. While in the firstdeployed configuration of FIG. 18c , the clinician can observe withfluoroscopy the positioning of the spacer 10 inside the patient and thenchoose to reposition the spacer 10 if desired. Repositioning of thespacer may involve undeploying the arms 14, 16 by rotating the spindle86 via the second assembly 104 to rotate the arms into any one of themany undeployed configurations. The spacer may then be re-deployed intothe desired location. This process can be repeated as necessary untilthe clinician has achieved the desired positioning of the spacer in thepatient. Of course, inspection of the spacer 10 may be made viafluoroscopy while the spacer 10 is in an intermediate or partiallydeployed configuration such as that of FIG. 18 b.

Even further advancement of the actuator shaft 50 via rotation of thesecond subassembly 104 from the first deployed configuration results inthe spacer 10 assuming a second deployed configuration shown in FIG. 18d, if the spacer 10 is so configured as to allow a second deployedconfiguration. The second deployed configuration is an extendedconfiguration as described above in which the superior and inferior arms14, 16 extend transversely with respect to the longitudinal axisoutwardly in the direction of the arrows in FIG. 18d . The spacer 10 isconfigured such that the outward translation of the arms 14, 16 followsthe rotation into 90 degrees and is guided by the length and shape ofthe openings 28 in which the arms 14, 16 move. Once deployed, thesuperior arm 14 seats the superior spinous process and the inferior arm16 seats the adjacent inferior spinous process. Such extension may alsoprovide some distraction of the vertebral bodies.

Following deployment, the second assembly 104 may be removed. Control114 is rotated in the opposite direction to release the body 12 from theinstrument 80. The insertion instrument 80, thus released from thespacer 10, is removed from the patient leaving the spacer 10 implantedin the interspinous process space as shown in FIG. 19. In FIG. 19, thespacer 10 is shown with the superior arm 14 seating the superior spinousprocess 138 of a first vertebral body 142 and the inferior arm 16seating the inferior spinous process 140 of an adjacent second vertebralbody 144 providing sufficient distraction to open the neural foramen 146to relieve pain. As mentioned above, the shape of the superior arm 14 issuch that a superior concavity or curvature 45 is provided to conform tothe widening of the superior spinous process 138 in an anteriordirection toward the superior lamina 148 going in the anteriordirection. In general, the superior arm 14 is shaped to conform toanatomy in the location in which it is seated. Likewise, as mentionedabove, the shape of the inferior arm 16 is such that an inferiorconvexity or curvature 47 is provided to conform to the widening of theinferior spinous process 140 in an anterior direction toward theinferior lamina 150. The supraspinous ligament 152 is also shown in FIG.19.

The spacer 10 is as easily and quickly removed from body of the patientas it is installed. The instrument 80 is inserted into an incision andreconnected to the spacer 10. The shaft 50 is rotated in the oppositedirection via a driver 104 to fold the arms 14, 16 into a closed orundeployed configuration. In the undeployed configuration, the spacer 10can be removed from the patient along with the instrument 80 or, ofcourse, re-adjusted and re-positioned and then re-deployed as neededwith the benefit of minimal invasiveness to the patient.

Any of the spacers disclosed herein are configured for implantationemploying minimally invasive techniques including through a smallpercutaneous incision and through the superspinous ligament.Implantation through the superspinous ligament involves selectivedissection of the superspinous ligament in which the fibers of theligament are separated or spread apart from each other in a manner tomaintain as much of the ligament intact as possible. This approachavoids crosswise dissection or cutting of the ligament and therebyreduces the healing time and minimizes the amount of instability to theaffected spinal segment. While this approach is ideally suited to beperformed through a posterior or midline incision, the approach may alsobe performed through one or more incisions made laterally of the spinewith or without affect to the superspinous ligament. Of course, thespacer may also be implanted in a lateral approach that circumvents thesuperspinous ligament altogether as well as in open or mini-openprocedures.

Other variations and features of the various mechanical spacers arecovered by the present invention. For example, a spacer may include onlya single arm which is configured to receive either the superior spinousprocess or the inferior spinous process. The surface of the spacer bodyopposite the side of the single arm may be contoured or otherwiseconfigured to engage the opposing spinous process wherein the spacer issized to be securely positioned in the interspinous space and providethe desired distraction of the spinous processes defining such space.The additional extension of the arm(s) subsequent to their initialdeployment in order to seat or to effect the desired distraction betweenthe vertebrae may be accomplished by expanding the body portion of thedevice instead of or in addition to extending the individual extensionmembers 14, 16.

The extension arms of the subject device may be configured to beselectively movable subsequent to implantation, either to a fixedposition prior to closure of the access site or otherwise enabled orallowed to move in response to normal spinal motion exerted on thedevice after deployment. The deployment angles of the extension arms mayrange from less than 90 degrees (relative to the longitudinal axisdefined by the device body) or may extend beyond 90 degrees and remainstationary or be dynamic. Each extension member may be rotationallymovable within a range that is different from that of the otherextension members. Additionally, the individual superior and/or inferiorextensions 42 a, 42 b, 44 a, 44 b may be movable in any directionrelative to the strut or bridge extending between an arm pair orrelative to the device body in order to provide shock absorption and/orfunction as a motion limiter, or serve as a lateral adjustmentparticularly during lateral bending and axial rotation of the spine. Themanner of attachment or affixation of the extensions to the arms may beselected so as to provide movement of the extensions that is passive oractive or both. In one variation, the saddle or distance betweenextensions 42 a and 42 b or between 44 a and 44 b can be made wider toassist in seating the spinous process and then narrowed to secure thespinous process positioned between extensions 42 a and 42 b or between44 a and 44 b.

The preceding merely illustrates the principles of the invention. Itwill be appreciated that those skilled in the art will be able to devisevarious arrangements which, although not explicitly described or shownherein, embody the principles of the invention and are included withinits spirit and scope. Furthermore, all examples and conditional languagerecited herein are principally intended to aid the reader inunderstanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

We claim:
 1. A method for implanting a spacer, the method comprising:coupling an insertion instrument onto the spacer by inserting prongs ofthe insertion instrument into notches in a drive element of the spacer;while the spacer is coupled to the insertion instrument, moving thespacer into a subject by inserting the spacer and the insertioninstrument through a supraspinous ligament of the subject to positionthe spacer directly between a first protrusion of a first vertebra ofthe subject and a second protrusion of a second vertebra of the subject,and rotating the drive element which translates an actuator element suchthat the actuator element causes a first arm of the spacer to rotate toreceive the first protrusion of the first vertebra of the subject and asecond arm of the spacer to rotate to receive the second protrusion ofthe second vertebra of the subject; and separating the insertioninstrument from the spacer while the first protrusion is held by thefirst arm and the second protrusion is held by the second arm.
 2. Themethod of claim 1, further comprising holding a body of the spacer whilerotating the drive element of the spacer relative to the body.
 3. Themethod of claim 1, further comprising holding a body of the spacer whilecausing the drive element of the spacer to rotate relative to the body.4. The method of claim 1, wherein separating the insertion instrumentcomprises removing the prongs from the respective notches to separatethe insertion instrument from the drive element.
 5. A method forimplanting a spacer, the method comprising: coupling an insertioninstrument onto a spacer that has arms with U-shaped ends by insertingprongs of a driver of the insertion instrument into notches of thespacer; and operating the insertion instrument by rotating the driver todrive an actuator of the spacer to gradually deploy the U-shaped ends ofthe arms such that the deployed U-shaped ends hold adjacent spinousprocesses of a subject while the insertion instrument extends out of thesubject, wherein the insertion instrument is positioned through asupraspinous ligament of the subject when deploying the U-shaped ends ofthe arms; and separating the insertion instrument from the spacerpositioned between the adjacent spinous processes.
 6. The method ofclaim 5, wherein the insertion instrument has a longitudinal axis thatis parallel to a longitudinal axis of the spacer when the insertioninstrument is coupled to the spacer.
 7. The method of claim 5, whereinthe spacer and a portion of the insertion instrument within the subjectare kept directly posterior to a spine of the subject while deployingthe U-shaped ends of the arms.
 8. The method of claim 7, furthercomprising inserting the insertion instrument into the subject using amidline approach.
 9. A method for implanting an interspinous device in apatient, the method comprising: inserting prongs of a driver of aninsertion instrument into notches in the interspinous device to couplethe insertion instrument onto the interspinous device; inserting theinterspinous device and a portion of the insertion instrument through amidline incision in the patient; positioning the interspinous devicebetween a first protrusion of a first vertebra and a second protrusionof a second vertebra; rotating the driver of the insertion instrument togradually deploy the interspinous device such that the interspinousdevice holds the first and second protrusions; and releasing theinsertion instrument from the interspinous device positioned directlybetween the first and second protrusions.
 10. The method of claim 9,further comprising rotating a threaded spindle of the interspinousdevice by rotating the driver such that the threaded spindle drives anactuator of the interspinous device, wherein the actuator is configuredto move through a body of the interspinous device to cause expansion ofthe interspinous device.